Haley said Monday she’s thankful for the tremendous response in just 18 days. She says the forum will provide GOP contenders an opportunity to tell voters their stance on issues in a “substantive, respectful and unifying way.”

The six-hour forum will feature candidates taking the stage one at a time to answer questions from Haley, Needham and conservative activists. The event is free.

There are 17 GOP candidates.

All candidates who have a Real Clear Politics polling average of at least 1 percent for August will be invited.